Population had increased tremendously, temperatures had risen enough to reduce ice at the poles to a fraction of what it used to be, so ocean levels have gone up as well.

Instead of fighting the water and keeping it out, cities started to embrace and make use of it. A new city block was designed as a building block for cities.
Buildings were composed of cubes; one block was made of four towers of six cubes in the middle, 3 cube towers at the sides and one cube buildings at the corners.
This provided more light and a better view for most residents. Each cube in a tower was seperated by a green floor; a mostly open area set up as a public park. The roof got the same treatment.

Canals inbetween the buildings provided the necessary capacity to house the extra water coming in during stormfloods and provided a method of transport.
Tubular construction running through the middle of a block housed the freeway for road transport and tracks for hanging trains underneath it.
Walkways spanning the distance between the roofs of the 3 cube towers and the same floor of the six cube towers added another level to get around the city for pedestrians and cyclists.

Cities created artificial islands between the blocks for farms, beaches and forests. In the tropical zones the rate of city blocks to jungle areas could get as high as one to one.
An often occuring plot for movies was wild animals invading the city or unknown creatures dragging people back into the dark forest or jungle.

The dystopian version is made up of mostly large towers grouped much closer together, no green floors, lots of debrie and trash, lonely alleys, a lot of rain.